chunking pattern

# General pattern for a data "chunking" process to prevent a server from hitting memory limits
# when calling .update() or .delete() on large amounts of data. In this example,  we enter an 
# infinite loop, then keep deleting 1000 records at a time until the records are exhausted,
# then exit the loop. You can't call .update() or .delete() after taking a slice, hence the need 
# for two queries rather than one.

t = Territory.objects.get(name="some-territory")

while True:
    loc_ids = Location.objects.filter(territory=t)[:1000].values_list("id", flat=True)
    locs = Location.objects.filter(id__in=loc_ids)
    if locs:
        print(f"Deleting 1000 locations starting with {loc_ids[0]}...")
        locs.delete()
    else:
        print("Done")
        break